Google does some interesting things. Ngram Viewer which I found about just today is one such. To know what the Ngram viewer does, we first need to know what an Ngram is. Well, according to Wikipedia, an Ngram is “a subsequence of n items from a given sequence.” If you just wanted to know how often a single word appears in a whole book, or a series of books, it would be a unigram for the word. Similarly, there would be bigrams for pairs of words, and n-gram for a group of n words.

So, what Google’s n-gram viewer does is, it looks for a word or group of words in all the books scanned by Google Books — millions of them — and tells us how often the words have appeared in those books. This gives us an idea of how trends have been, even before the Internet.